Taiwan Strait is a shallow shelf channel linking the East China Sea （ECS） and the South China Sea （SCS）. During winter monsoon

cold Min-Zhe Coastal Water （hereafter MZCW） rich of nutrients generally dominates the northern Taiwan Strait; warm oligotrophic Kuroshio water （hereafter KW） and Soiuth China Sea Water （hereafter SCSW） from SCS intrude into the southern Taiwan Strait. Nevertheless

Kuroshio intrusion into the Taiwan Strait was found to be stronger than usual during winter monsoon of 1998

as observed by a satellite instrument

AVHRR

and a CTD in situ. In situ data were obtained in the northern Taiwan Strait during a winter cruise of 1998 from February 20th to March 8th

which suggested that warm streamer as indicated by 18℃ isotherm approached as north as 26°N. A series of AVHRR SST daily images covering the whole Taiwan Strait region

which were got on Feb.8th

Feb.25th and Mar.13th

respectively

confirmed that warm water mainly intruded into the Taiwan Strait from the southernmost tip of Taiwan

heading northeastward along the Penghu Channel. There were also some evidences hinting that warm water coming from the Kuroshio mainstream off Taiwan in the Pacific ocean

intermittently influenced the northern Taiwan Strait from the northernmost tip of Taiwan. This effect seemed to be weakening while the northeastward Kuroshio intrusion was strengthening from February to March. The mainstream of Min-Zhe Coastal Water was thus forced to go southwestward along the Mainland coast into the southern Taiwan Strait. This process probably heated Min-Zhe Coastal Water and led to the injection of nutrients into the southern Taiwan Strait

enabling unusual high winter Chla along the Mainland coast

especially in the southwestern Taiwan Strait

as shown by a single SeaWiFS Chla imagery on March 27th. Observation in situ from February to March also confirmed Chla enhancement in the northwestern Taiwan Strait. Chla content reached as high as ca. 5 mg/m+3

which were 4 times greater than that was observed in 1995. It was suspected that the unusual strong Kuroshio intrusion and the corresponded Chla enhancement in the Taiwan Strait during winter 1998 were probably related to the very strong tropic E1 Nino of 1997～1998.